Trick me into paying twice for changed booking.

Sham & Bad correspondance and response only at night, lots of emails from many agents to make changes. I paid $38 and changed my returned ferry tickets in January to April 2023 due to I had Covid at the time. I had to change my dates again due to Covid again grrr. Through correspondance of emails I get a message stating my ferry was sailed in January due to I did not pay $227 to change my ferry dates to April. After sending proof of payments and screenshots of confirmed dates, invoice changed for my ferry Direct Ferries tell me they sent me the wrong payment amount of $38 it should have been $227. I emailed and said that is your mistake not mine, I would like a full refund of my $500 I previously paid and the $38, they would only refund the $38 would not take responsibility of there mistake. I recommend to go directly through NZ Interislander or Bluebridge to book online. Direct Ferries is based in London.