It seems clear from your numbers that the arrears are due solely to being overcharged by the lender. There is no other cause as far as I can see.
Tenants move out ,.house destroyed needs 4 to 5 k spent on it .
Not sure its fully down to the overcharging. There is another major factor in this that the tenants destroyed the house so it could not be rented out so the income stream disappeared. Had the house not been destroyed by the tenants, then the arrears would not have been as bad.
If you as a landlord had selected different tenants or you had inspected the property more frequently it may also have avoided the need for the refurbishment. I don't think you can blame the bank for the tenants you selected!
If the tracker rate was correct 1.1% above the btl would show a nice profit (€5800) and money would be available from savings to refurbish the house .
Lack of funds is due to overcharge
That's assuming the savings had not been spent and were available solely for this. I can fully accept there is a negative cash flow impact as a result of the overcharge.
In theory you could also blame the government, due to increased taxes such as property tax, NPPR, reduction in allowance interest rates etc also caused a negative cash flow impact.
Was it all down to the overcharge? No, I don't think it was. In any 8 year period, it will be very difficult to pin everything on a single issue. It is a combination of factors - it does not make it any better or any worse though!
But yes I know you are talking about family homes , but I'm sure this scenario could be related to a family home
Not sure how to be honest, as the issue here is a combination of increased outgoings and reduced income as a result of the overcharge. The function of a family home is not to generate income, so hard to be hit on both sides. Any loss of income is probably not a result of the overcharge.
At an absolute stretch, you could say that the family were renting a room for 10,000 euro to help with the mortgage. However, due to the additional stress the mortgage caused, including a decision to dramatically reduce the heating costs, the tenants moved out as the house was no longer a nice place to live. The mortgage fell further into arrears as a result.
But the tenants could have moved out for any reason - including nothing to do with the family, so would be a hard one to argue.