Ive had mine done since the summer. I think I’ve only used a mitt to wash it maybe 4 times. I’ve started using a ph neutral traffic film remover. I top it up after nearly every wash with auto finesse aqua coat. Maybe try something similar to top it up? I bought the gtechniq top up but haven’t used it yet so I can’t tell if that’s much better, it definitely takes a couple of days for the dirt to stick to mine and I find it’s not as prone to having dirt stick to it as before the ceramic. I’ve noticed my fathers car that was done by a dealer less that a fortnight ago is already deteriorating so there is obviously different levels of deterioration for different coatings.
If I was you I’d get a second opinion by someone and after that make a decision whether you’ve got what you paid for or not.