GCSE lost certificate AQA

Hello.I never knew that I had to collect my GCSE certificates from school because school has never contacted me, so now I need GCSE certificate to prove my English grades and I haven’t got them on me. I have ordered a replacement from AQA website and was told that it can take 20 working days or more because it is busy time. And I’m really stressed about it, because university starts really soon and they still haven’t accepted me. Someone who has ordered and received certificates before, can you please tell me how long did you wait for your certificates to be delivered in London? Thank you