First bit of advice: Calm down and stop bumping ancient and largely unrelated threads. This whole thing reads like your father made some slightly unusual arrangements and you’re jumping to conclusions and being a drama queen for the sake of it.
No ISP I have ever worked for or dealt with (to my knowledge) will change the account name in the circumstances you describe without having signed paperwork from both parties, it’s a question of liability, COSAR potentially needs updating, a credit check needs to be done and they need to know where to send the bill to for the former account holder, they will also usually verify the request with each party. However slow that may be, I assume they told you the ETA/SLA at the start, that likely doesn’t start till they received correctly filled out paperwork etc. If it’s beyond that timescale, then contact them and ask for an update, but as you are neither the ex manager or your father, expect to get nowhere without one of them with you, as from TT’s perspective this has absolutely nothing to do with you.
Faults wise you’re mistaken, if a fault occurs anyone can report it. Also disconnecting the router will still leave the line active, you can’t take another providers service on it and your father would still need to pay to have another line installed and I’m guessing the management contract your father signed will stipulate he is also liable for the cost + fees, which is just going to make things worse as the former property manager then gets to take him to court for non payment and it’s pretty obvious how that would end. Line cost + non payment fee x 3 months, collections costs, the stated fees from the management company contract, statutory interest, the small claims court fees, legal costs and loss of earnings etc. Don’t be that guy....
As a short term fix why not go and see the manager, be polite and don’t get excited, they probably don’t want to have the agro of paying for services on a property they don’t manage either, phone TT together and ask for an update, while you’re at it get them to put a password on the account and have you/your father noted as being able to deal with the account. Either way being a drama queen will just cost you more agro and your father more money.