If they screwed over the previous LL, the previous LL may have said anything to get them out.
I don't see how their financial issues are your problem. Have the 14 day warning issued.
you mean there is no reason not to pay rent
Sounds like another fob off excuse, anyone can write a cheque and send a pucture of it to you, without money in your account it is meaningless.
If you have not received any money in the last three months then you need to protect yourself from any more nonsense.
Tell them you giving them notice for all arrears to be brought up to date and if by the end of that notice the arrears are not cleared they will be issued with a termination notice.
Plenty of good tenants out there waiting.
If you used a generic lease you’ll find a clause about leaving the property empty for more than 30 days.
After that assume that they have moved out. Simple dunk the stuff, keep receipts to use against deposit which is forefeitted and relet