Last Resort

Hello all, I am currently drawing £723.06 p.m. from my SIPP. Also in receipt of State Pension income at £943.60 p.m. I recently took an ad-hoc sum from my SIPP in July of £27,500 - expecting to be netted down to £22,000 (my required sum). The £27,500 was instead taxed down to £19,738 after having £7,762.17 deducted from this. The regular payment of £723.06 in that month also became taxable and netted to £519 after having £204.09 taxed. Total tax paid in period 4 amounting to £7,966.26 (effective rate of 28% in that pay period). I then took an additional £3,110.33 in August (still period 4) in order to hopefully make up the shortfall to my required £22,000 net lump sum. This income had £1,244 taken in tax - an effective rate of around 40%. My payslips indicate a normal tax code 1257L - no W1/M1 applied. I therefore thought that I would have just received my gross income net of the standard 20%. So £27,500 giving me £22,000. Is HMRC assuming I am to receive the lump sums monthly for the rest of the tax year and this is why they have been hit harder than expected? How do I remedy this asap? I would rather not wait for calculations to be made by tax year end as I am requiring the initial net sum quite urgently, but would rather not keep taking increasingly taxed ad-hoc withdrawals to get there.