I think you should contact the bank immediately, words like Scammed and possibly Elder Abuse make the banks take notice.
Obviously CAB as others have said.
I signed up to a Toolstation cash back scheme, I wasnt aware I was taking out a chargeable subscription.
The subscription was weekly at £30 through my business, lapse on my part, I don't often look at my statements. I rang the bank, they said they couldn't stop the subscription as it wasn't traceable or registered and they couldn't refund the £450.00 already taken.
In other words I would have to pay £120 for this subscription a month for the rest of my life, they were adamant they couldn't stop it.
I simply said, make me an appointment please at my local branch, why they asked?
So i can close all my accounts with you, that will stop it.
Subscription blocked £450.00 reimbursed.
What I'm saying is you really have to dig your heals in with banks and fight for your Dad.
As far as the roofer, find out who it is and berate him all over social media.
A question was on a another forum, Do you feel sorry for ripped off customers? I said I didnt. But I do feel sorry for your Dad, being a tradesman myself it really does boil my p*ss when elderly people get ripped off.
Good luck.