Dissatisfied customer

I bought a vehicle via Webuycars in March, i had requested a service plan to be added of which it was done. Upon collecting the vehicle i was told they under quoted me on the service plan and they will cancel it, which was quite unfair on my end as i had requested for it to be added. Fast forward to now i have noted my instalment includes this service plan they supposedly cancelled, i have complained on their customer complaints page and got referred to someone who will assist me, till to date no one has made means to resolve this for me. My vehicle is due for a service soon & i need this service plan issue to be resolved. I am honestly so disappointed in the kind of service from Webuycars.