Oh God they are still charging you interest!!? It's going to take you a decade of paying off £300 pm. You have already said it's unsustainable for you, and they could still default you on a whim anyway at any time.
That £9.86 you have left over every month because of this, is that going to cover, a new set of tyres for your car, Dental treatment, new shoes, clothes, one of life's hundreds of potential emergencies that need money in reserve?. It's making you financially vulnerable.
If you have a guarantor to cover you in case you need to rent again in the next few years, and you aren't planning to apply for a mortgage any time in the next 2 years, you're not bothered about car leases etc, I'd stop payment, and wait for the mountain of letters. It will be over quicker that way, and be far easier on your finances.
Naturally you would need to keep your creditors informed whenever you change address though, important so that if , and it's a big if they send a claim form, you can respond and defend.