Is your account run by the person that you signed up with ? Or did a 'bait and switch' happen ?
Is your account run by the person that you talk to on the phone ? Or do they just do customer service ?
Do you pay as a percentage of your Google spend ?
If you have a small number of services are you paying over £750 per month plus Google spend? London agencies often charge a minimum of £1000 per month.
A good way to spot a cowboy is cold calling. Have you ever bought anything good from a cold call ? These people work from a script designed to sell to the uninformed or weak-minded. If this is you, I've got a bridge in London I'd like to sell you.