Requesting Import VAT & duty repayment on defective goods

Hey everyone. I bought online from outside of the UK, the item is defective and I am returning it to the sender. This was a private sale. The item arrived here via Royal Mail, who also collected the fees due. I want to reclaim the import VAT and duty from HMRC. I completed a C_E1179CDS because the description of this form ("use this form to claim repayment or remission of customs charges on goods which are not in accordance with the contract, defective, or damaged before they are cleared at customs") made the most sense in my case. The HMRC representative replied the want a C285 form instead ("apply for a repayment of import duty and VAT if you've overpaid") I asked them why (I am genuinely curious, I need to understand this process) hopefully they will get back later. CDS means Customs Declaration Service, and therefore I should have a Movement Reference Number when I claim. However on the original customs declaration (CN22) no MRN is stated and none of the customs documents from Royal Mail show this number either. Their reference number on their payment request is not 18 digits and does not correspond to the format of the MRN (year, country code and the "automatically generated alphanumeric reference") I read on this forum, if I received the defective item via Royal Mail, I should be able to use a so called BOR286 form to ask repayment. The description of this form says I need to complete this form if I believe "that Customs Duty or import VAT has been incorrectly calculated on your imported item." I don't believe the calculation is incorrect per se, I believe the description of the C_E1179CDS covers what I need more accurately. I called Royal Mail regarding the MRN and they said they don't have that and eventually they hung up on me. I am confused and I am wondering if there's anyone who can explain me what's going on here?

I received a reply to my email from a HMRC representative, I quote the relevant details here for future reference: "Your claim for overpaid Import VAT & Duty can’t be accepted at the moment, This is because you have not included an MRN for the parcel – this means we are unable to deal with this claim. If you only have a ParcelForce / Royal Mail tracking number then you will have to complete a BOR286 form and send it to the address on the bottom of the claim form attached. These claims are dealt with by Border Force who are a different Government body to HMRC, therefore we are unable to help with your claim any further. Please send the claim form and all supporting documents to the following address; Border Force Coventry International Hub Siskin Parkway West COVENTRY CV3 4HX Once they process your information they may refund you directly or pass this onto us but we need information from their system that only they can provide at this stage before we could issue the repayment."

Hi John
Please contact our International Trade Team as below:
Imports and exports: general enquiries
Thank you.