Avoid dealing with Skipton if at all possible

As with most of us who need a mortgage and don't have the time to 'shop around' I approached a recommended broker who got me a mortgage through Skipton.
The broker clearly had a relationship with the building society and so he managed to get everything sorted and got me a 2 year fix mortgage.
So far so good, no complaints.

For two years my relationship with Skipton was for me making the necessary monthly amount available in my bank account and for them to take it.
So far so good, no complaints.

Then came the end of the fix term. I made the mistake of taking the easy route of sticking with Skipton for another 2 year fix term rather than looking around or approaching a broker.
Skipton's agents were/are good as gold when they talk to you on the phone (email is another matter, rude and not helpful) and full of assurances of what's going to happen when and how.
But, did things happen the way they assured me? No!

I made a lump sum payment which I was assured I was allowed to make and called to confirm before making the payment. Two days after making the payment I received a letter saying I have been charged penalty interest for making the over payment!
Called them again and as usual their agent were good as gold and assured me this will not happen and that I will receive a letter confirming that this is not the case. Still waiting for that letter.

Then came the new monthly repayment amount that they quoted in the mortgage offer letter which I obviously was happy with and signed and sent back.
The I receive a letter which has a different monthly amount to that of the mortgage offer letter. I called them back and they assured me the letter was sent out in error and that the correct amount will be taken out come the start of the new fixed term.
You can probably guess what happened next!

The payment taken out was the higher and incorrect amount.
Left a message on their site with detailed description of the issue (so that I don't have to go through the same thing for the fourth time in two weeks) and asked them to call me back. I get a call back asking me, "how can I help you"! Arggghhh!

The issue is still on-going and not resolved!

So, basically my advice is, avoid dealing with Skipton if at all possible or be prepared for the pain that is most likely to follow.