Welcome to the Community, I'm massively sorry to learn about the problems you're experiencing with the Catch Up service at the moment.
I've been able to locate your account to run some tests on the set top box for you, we're not detecting any errors at the moment although if this issue is intermittent it won't show up on our side every time.
In order to help us identify this issue as soon as possible, could you answer these questions? Sorry for the question time!
Do you notice this issue occur at certain times of the day?
Is this affecting all Catch Up programs?
Is this affecting more than one set top box? (If you have one)