UK Mortgage Help: Why would a lender Really push for fee paid and slightly higher fixed rate?

Today I went to see a mortgage lender at the UK Post Office. I wanted to choose a 15% LTV 5 year fixed at 3.65%, then 4.49% variable after. With this loan I pay a £995 arrangement fee and a £240 valuation fee. The lender seemed willing to do that.
A couple of days later, I go in to make final arrangements on the above loan, when, at the last moment, she INSISTS that I do a slightly different rate. This time she wants me to do a 15% LTV 5 year fixed at 3.99%, then again a 4.49% variable after. But with this loan, I wouldn't have to pay the arrangement fee and the valuation fee. I also get refinancing help if I want: the Post Office would pay for the re-mortgage legal fees (their solicitor -- not mine). Does this sound great?
I did the math and found that I would only save about £4 per year (fixed years) with this new higher interest rate but no fee loan. The only real difference I could see was that had no fees/more assistance and the other had fees but seemed more simple. In fact, all the loans they offer have the two options. I immediately began to suspect a "bait and switch" tactic going here.
When I told her that I wanted to go with the first (fee included) loan, she became VERY ANGRY and flatly refused to process my loan. I had to go home and apply online and I was accepted.
Am I missing something here? Why did she INSIST on the second option. And why did she really refuse my first preference? Does anyone know?

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