Awarded max maintenance loan by mistake

My son applied for student finance to start university in September 2025.
Me and his mum live together and we both work. Based on our income he should receive close to the minimum maintenance loan which is around £4,900. However he has been awarded the maximum maintenance loan of around £10,500.
I have phoned student finance several times but they seem unable to do anything. They constantly put us on hold and say they will check this and check that but they never discuss the details and tell us that everything seems to have been done correctly. They don't tell me any more than we can see from our student finance accounts.
I am at a loss as to what to do.

Our son is under 25 and our income wasn't lower, it has been very stable for about 6yrs due to covid.
His mum's supporting app was done online and my supporting app had to be done on a paper form via post as I had an account from the 1990's but the help line couldn't gain access to it.
His mum works part time and earns less than 20K, so to me it seems as if they think I earn nothing. I wish I had ignored the email about supporting his application so he would only of got the minimum amount and we could of avoided all this hassle. It seems the people I speak to on the phone don't seem to be able to do much apart from check everything was submitted correctly.