I am looking for some advice please.

I was originally booked on BA0530 LHR to SPU 14 Jul 2024 09:10 - 12:45.
BA0530 was cancelled couple of hours before departure and I had to rebook onto the next flight BA0842 LHR to SPU 14 Jul 2024 12:50 - 16:25.
BA0842 landed at 16:25, 4 hours later then the originally booked flight and therefore the compensation due under EU261 is £350.

I submitted a claim for compensation on 15/07, and a reply came a few weeks later:

“Unfortunately, we’re unable to process your claim as the flight details you provided do not match our records for EU261 eligible delayed or cancelled flights.”

I suspect they are suggesting I made an error when filling out the claim.
So I submitted the above response with exact flight numbers and times on 15/08.

No news since.
Should I carry on waiting?