Looking for a damp proofing specialist

HI,

We have a damp problem in our garden studio. Looking for recommendations for a local person/company  who's experienced in this. Doesn't have to be a specialist company per se, just someone who can fix the problem. The level of the garden studio is lower than the next door garden so the suspicion is that damp is coming through the wall from the earth on the other side which obviously can't be cleared!

 many thanks

 sue