Sounds to me like they should have used the word 'received' instead of accepted.
I can't speak for Ryanair but there are many reasons why a request for a refund would be refused. Also, I was under the impression that communication with their customer relations had to be in actual writing as opposed to email or telephone. I guess they figure that getting it together to write a letter, print it, sign it, pop it into an envelope, buying a stamp and posting it might be too much trouble for a percentage of their customers.
Again, I can't speak for Ryanair but I have spent some time in BA customer relations and it could take a good 4 weeks to get an acknowledgement out to a passenger complaint, then around 6 weeks to investigate and reply, then around 4-8 weeks to get a refund (different to a goodwill payment) out to a passenger, depending on the circumstances.