Getting charged Customs/VAT for my owned stuff I shipped thru mail upon moving

I moved here in November of last year. I could not bring everything I owned and wanted to move with me at the time, so I have had my father ship a few boxes since then. I keep getting Customs/VAT charges despite this stuff all being obviously pre owned, obviously used, and obviously sent from my father's residential address. My father may have mislabelled the shipping the first time, but he definitely didn't the second time, and those still just got a charge of well over 200.

What should I do to fight this? We paid the first time just out of frustration and the tiny deadline they give you, and because we already spent so much on the actual shipping. But enough is enough this time. They are making up completely arbitrary values for the items and telling me I owe on this stuff. Please help This stuff is all mostly sentimental stuff or old childhood things, and I have owned them for a long time. As far as I understand it, I should not be paying customs/vat on this.

Thank you for your time.

Edit: This 2nd charge is for a package they already gave us months ago. It was an invoice by mail.

I moved here in November of last year. I could not bring everything I owned and wanted to move with me at the time, so I have had my father ship a few boxes since then. I keep getting Customs/VAT charges despite this stuff all being obviously pre owned, obviously used, and obviously sent from my father's residential address. My father may have mislabelled the shipping the first time, but he definitely didn't the second time, and those still just got a charge of well over 200.

What should I do to fight this? We paid the first time just out of frustration and the tiny deadline they give you, and because we already spent so much on the actual shipping. But enough is enough this time. They are making up completely arbitrary values for the items and telling me I owe on this stuff. Please help This stuff is all mostly sentimental stuff or old childhood things, and I have owned them for a long time. As far as I understand it, I should not be paying customs/vat on this.

Thank you for your time.

Edit: This 2nd charge is for a package they already gave us months ago. It was an invoice by mail.

https://www.gov.uk/moving-to-uk

Is this something that needs to be done all at once? I can't believe you have to pay, and then claim relief? I swear it wasn't like this 10 years ago?

You have a year to bring your belongings without tax.  This was introduced about 3/4 years ago.