Wecoolanycar dot com mobile service and is very good at what ho does but I suppose he's very busy at the moment but you can try
I went to this man http://www.skauto.co.uk/air_conditioning.php
and he found leak in less than 2 minutes. Something we coolanycar.com could not do even after 4 or 5 visits.
Which ever person you use, ask them how long it takes to the aircon, if they say any less than 30 mins, walk away.
I would strongly advise not using wecoolanycar.com