PERSISTENTLY LATE RENTAL PAYMENTS - SECTION 8 - POWERLESS LANDLORD?

Rent Arrears

I need competent advice and to discuss this with someone because I would rather have no income than have #$%^&*()@ in my property!:

Repeated late payment arrears by Tenant(s) based on a non-functioning focal point (as in not a heat source) gas fire.

This was not known to be not working by managing agent at outset of this tenancy as it must have stopped working in a previous tenancy and the requisite part no longer available as advised by the initial fireplace provider so condemned by Gas Safety Inspector providing requisite GS certificate.

This is outwith 03.07.2020 12 month AST (no break clause) tenancy as a material issue because gas water and heat is provided everywhere.

Relevant AST articles

1. 15 (c) not use any gas appliance..declared unsafe or disconnected from supply
2. 11 pay costs for any action inc. court fees...
3. 4 Landlord end tenancy with at least 60 days notice via section 21 notice
4. 2 quiet enjoyment does not preclude taking action ...fail to pay rent or be in breach...
5. 8 L/lord fulfils repair obligations (b)"to keep in repair and proper working order the installations in the dwelling house for the supply of water, gas and electricity and for sanitation 9including basins, sinks, baths and sanitary conveniences, BUT NOT OTHER FIXTURES, FITTINGS AND APPLIANCES FOR MAKING USE OF THE SUPPLY OF WATER, GAS OR ELECTRICITY)". Seems odd but there it is!!!

COVID-19 IMPACT AND EXTENSION TO NOTICE PERIODS
I want to serve section 8 notice (discretionary ground 11 - persistently late paying rent which has a 2 week notice period and be done with it however
From 27 March 2020 to 20 September 2020, I understand ongoing possession proceedings were suspended to protect tenants and homeowners from the impact of the coronavirus pandemic.
For notices served between 29 August 2020 and 31 March 2021 inclusive of, the minimum notice period is six months, unless exceptions apply

Given all of above and extended time limits before it gets to county court it seems I am powerless and have to suffer this * until expiration of the tenancy? There must be something!?

Thanks

David