Landlord threatening (implicitly) to include 'overlooked items as a gesture of goodwill' into the deductions if a dispute is raised.

TLDR: Moved out of a flat in May, and the landlord informed me about the deduction on 28th June. The stated deductions are circa £550. With £200 of labour charge, that has not been specified as to what. Other charges include cleaning fee, chair covers bed slat pins toilet seats etc. And staining that some items (one of them was genuinely our fault). When a clarification for the cost and the labour charge was requested, and mentioned that if this does not happen. They have now responded, sharing the receipts and details – still no mention of why the Labour cost is £200.

I have advised the landlords that I am considering disputing then deposit deductions with the TDS/DPS and the landlords have gotten back to me stating should I wish to raise a dispute with the TDS/DPS, then they will increase the deductions to claim for items which they have previously excluded “as a gesture of goodwill.” I feel that they are trying to threaten me into relinquishing my intention to dispute the original claim made. Does anyone have experience of this happening to them and should I raise a dispute, could the TDS/DPS make me pay back more than the original claim amount made by the landlords.