Phone call asking about difference between P60 and renewal information

Stroller133

I received a call from HMRC today. Basically my renewal income didn't match the RTI figure from my employers P60. This I think should not be abnormal as the renewal pack lists everything that can be taken off, and is the whole point of the renewal process to confirm CORRECT income figure as laid out by the tax credit rules. I explained the difference was due to gift aid donations, some employment expenses I incurred and was not reimbursed for and one week of stat paternity pay, so I could remove an extra £100 for that.
She said I would have to submit payslips with the gift aid and said expenses were not deductible. I don't gift aid via payroll and my reading of the renewal pack is that expenses can be deducted.

She then went on to say the only figure they accept is the gross P60 value - this is at odds with the guidance notes with renewal and tc825 form.
She did then say a letter from the charity might be accepted, but didn't give any clear response whether my interim payments would stand until I provide the evidence or whether they will assume my P60 is correct which would result in us owing money back from last year and massively reduce this years award - especially if they sought to recover the perceived overpayment from last year.
She also said if I agree with the P60 value she could finalise my claim today - in my view I would have been committing fraud (albeit where I lose out!) - I think one should either claim child tax credits using income calculated using the rules or not make a claim.
In the end the lady hung up, as she couldn't or wouldn't fully explain my situation. The worrying thing is she was finalising claims but didn't seem to understand what can be disregarded as income for tax credit purposes.
I called back using the helpline and the second lady fully understood that the grossed up gift aid, expenses and paternity should all be deducted and explained the letter would ask for evidence of these and once received my submitted income would be used. She also said more checks are being carried out this year.

I fully accept if the state are handing out benefits they are entitled to ask for evidence of entitlement, my frustration is I had all the evidence in front of me several weeks ago and did my self assessment at the same time and put it all away thinking it was done with. I would happily have sent it to then then if I had the option.

Could the first lady work for concentric? She seemed to be somewhere in between asking me to provide evidence of the deductions, friendly at first and suggesting my P60 value is the right one and suggesting that could be used. If I wasn't as savvy and confident of my situation when she said the P60 is the figure they are looking for, other may have thought they had got it wrong.

Sorry for rant - the last 5 years renewals have been the same and not had any come back before - I thought they may check with self assessment to verify renewal information.