Help my mortgage has been recalculated!

JC_Leeds

I'm currently in a fixed rate with Barclays until 2022. In December I noticed my minimum payment had increased by just over £100 per month
I rang them and couldn't get any sense out of the Call Centre who didn't explain why it had been recalculated.
I have made regular overpayments but don't think I've breached the 10% I'm allowed to overpay.
I received a letter from them explaining they had recalculated my payments and that my monthly amount would actually reduce by £50 in January however my online banking is still showing the increased payment they took in December ( original sum plus £100).
As far as I can gather they said they recalculated it due to my overpayments to put it back in line with the 13 years remaining. Is this usual on a fixed rate?
The Call Centre is overseas and is awful, can't see to speak to anyone in UK who understands or can explain this to me
Thanks

SonOf

As far as I can gather they said they recalculated it due to my overpayments to put it back in line with the 13 years remaining. Is this usual on a fixed rate?

It is if you select that option. When making overpayments you need to decide whether to reduce the balance or to reduce the payments at the review date (which is often set annually).

getmore4less

Overpayments reduce future payments not increase them.

More details needed?
How about some relevant numbers

A few months of amount owed, rate, payments.

Do you have a reserve you have been using?