Lender accuses me of breaching mortgage conditions?

Hi Richard, no it doesn’t sound fair, but your options may be limited. As it’s an interesting situation I put this through Google AI which came up with the following – you may find it useful:
“Having one single Joint AST agreement is your strongest point of leverage because it demonstrates the tenants are operating as a single household, not a traditional room-by-room HMO. If Early Repayment Charges (ERCs) apply, your immediate goal must be to avoid a costly remortgage by presenting a formal business case to your current lender.
1. Build Your Legal Case to Challenge the Fines – You need to prove to your lender that while the local council has redefined the property for licensing or planning purposes, the risk profile of your mortgage has not changed. Leverage the Joint AST: Emphasise to your lender that you do not have bedroom locks and the tenants have “joint and several liability”. This means they operate as a single family unit, which aligns with standard Buy-to-Let risk profiles rather than commercial HMO risks. Request a Consent to Let (CTL): Formally ask the lender for a temporary “Consent to Let” or a specific waiver for this tenancy. Argue that the breach was entirely involuntary due to retrospective local authority policy changes, not landlord actions. Involve a Professional Advocate: If the lender’s customer service team rejects your claim, escalate the issue through an industry body or specialist broker to challenge the fairness of the monthly fines.
2. Run a Cost-Benefit Calculation – If your lender refuses to back down, you must calculate whether paying the monthly fines is cheaper than breaking the mortgage and paying the ERCs. Use this step-by-step framework to evaluate your options: Calculate total remaining fines: Multiply the monthly fine amount by the number of months left on your fixed term. Calculate the ERC exit cost: Look at your mortgage statement to find the exact penalty fee for leaving early. Compare the numbers: If the total fines exceed the ERC plus the setup fees of a new HMO mortgage, it is financially logical to move lenders immediately.
3. Plan a Forced Remortgage (The Last Resort) – If the fines are exorbitant and the lender threatens to call in the loan, you will be forced to transition to a specialist HMO product. Find an HMO Broker: Standard high-street lenders will reject this property. You must use a specialist broker to find lenders who accept “unlocked, 3-bed sharer” properties. Absorb the ERC into the New Loan: Ask the new specialist lender if the ERC from your current bank can be added to the new loan balance to avoid a massive upfront cash requirement.”
I thought this was a pretty good assessment – hope it helps!

Hi Richard

I sympathise this is a very unfair situation.

I had a slightly different problem when Newham council had just introduced selective licensing throughout the borough.
Newham informed my mortgage company that I was operating a HMO. and they threatened to rescind the mortgage.

For about 15 years prior to this the house was let to 4 unrelated sharers and this was made clear on the mortgage application.

I eventually got them to see sense by insisting that the existing tenants were there when I took out the mortgage and I also sent them all the previous tenancy agreements going back several years to illustrate the point.