Overpayment confusion

A question about : Overpayment confusion

We have Ј5k and we want to make an overpayment on one of our debts but are a bit confused about which is the smartest option. Our debts are as follows and all have the option for overpayments:

1. BTL mortgage (thus interest only payments) of Ј110,000 at 4.24%
2. Mortgage for our family home of Ј113,000 at 3.95%
3. Personal loan of Ј12,000 (borrowed 4 months ago to renovate our home) at 9.9%

I initially thought the loan was the best option as its such a bad rate but I'm not sure if I'm right.

Any advice would be appreciated.

Best answers:

• Loan. Then mortgage.
  BTL bottom of the list if you pay tax and offset the interest against income.
• When I enquired with HSBC about making a one off overpayment, they said I will still pay back the full amount including the interest which was originally agreed but once the loan is fully settled they will refund the difference in interest for the amount of time which the loan was repaid early. Is this pretty standard practice?