Why have British Airways changed my flights to Danish Air Transport?

Morning all,
In April I am flying out to Athens to attend a training course.
I don't travel often but when I do I book BA.... Government preferred carrier, plus I trust the pilots (don't ask)
Anyhoo, both flights to and from were booked seperately not as a return flight.
Yesterday I received 2 seperate emails from BA saying they had changed my 'carrier' to DAT for both flights.

We wanted to let you know that there has been a change to the airline operating your upcoming British Airways flight to/from London Heathrow. We’ve had to make some adjustments to our schedule and have leased an aircraft from our partner, Danish Air Transport. This change is due to operational reasons and they will operate your flight on our behalf, so you can fly to your destination as planned. Rest assured, there will be no change to the service you receive onboard. If you're happy to continue with your travel, you don't need to do anything further. However, if you do not wish to travel on this service, we have some options available to you, including changing to an alternative British Airways operated service.

I had paid extra to reserve my seat on both flights.
Hunting around to find info on DAT (never heard of them) I stumbled across this forum called Flyer Talk. Guess what the topic was?
BA to wet-lease DAT aircraft, rebooking policy?
It would appear a whole raft of emails have been sent out to BA customers flying, from not just Heathrow airport and not just to Greece.
What's really going on?
Is it because of the increasing issues with Boeing planes?
Is it because since p(L)andemic BA have plane and staffing issues? I doubt this one.

Something has always niggled me about this trip regarding the travel and I just dismissed it because so far this year.... if it can go wrong it has. But now this email has sent me over the edge. What the hell is going on with BA that they have changed a raft of flights to and from Greece, and a few other countries if you pop on Flyer Talk to see some of the comments/posts?

Please can seasoned travellers help me out here as this has made me very nervous about my flights, and not happy having paid extra for my reserved seats with no mention in email about that still being guaranteed.
There is a phone number for me to change flights back to BA, but I don't want to do that until I get some feedback from my ATS friends.
Thanking you in advance
Rainbows
Jane

a reply to: angelchemuel

Just as a guess, BA has had to shut down some of their aircraft for inspection/safety reasons.

Anything made by Boeing is going to be under close scrutiny.

a reply to: DAVID64

Thank you, I was wondering if this was a Boeing issue, especially given the amounts of flights that they have changed.
Maybe that's why I was having 'pre-emptive' collywobbles about the BA flights and I should be 'glad' I'm now travelling on a DAT flight whose plane is not a Boeing from the reports on Flyer Talk?
Rainbows
Jane

Where's Zaphod when I need him!

Rainbows
Jane

a reply to: angelchemuel

It’s a short haul flight. It’s an Airbus anyway. More than likely shortage of airplanes and or crew would be my guess.

Airlines occasionally will wet lease airplanes during the busy season.

a reply to: Donnchadh03

Thank you.
I didn't think that DAT used Boeing's from the forum link.
Rainbows
Jane

originally posted by: angelchemuel
a reply to: Donnchadh03

Thank you.
I didn't think that DAT used Boeing's from the forum link.
Rainbows
Jane

They don't. It looks like the Danish Air fleet is basically the same aircraft type that British Air would be flying anyway. If so, you probably would still have the seats you paid for. You should be able to get that information online. Look up your reservation using the flight reservation number that BA sent you, and click on the "Flight Details" text. That should bring up a box that will tell you the aircraft type they intend to use. Also, there should be a seat map associated with that flight that will show you whether you still have the same seats.

a reply to: Boomer1947

Thank you Boomer, I shall do that today and take it from there tomorrow with BA if I don't have a reserved seat.
Rainbows
Jane