Most unpleasant experience and a lot of stress:
Check-in surveys are everything but independent, major faults with the property don't get listed (e.g. cracked double glazed window).
Check-out surveys are done with a magnifying glass. Problems with the property such as leaking radiators on the second floor causing central heating not to work in December and soaking the kitchen ceiling resolved in 3 days.
We have re-decorated the entire house, fitting new carpet in one of the rooms, bought leather sofa set the replace the cloth one in which we found a train ticket from 1994. Despite this, the deposit was disputed at the end.
The Bulgarian bloke who was playing manager at the time was as helpful as the dead mice I found underneath the kitchen cupboards when we moved in, refusing the provide information on why the deposit will not be returned.
When deciding whether to go to them, don't forget to factor-in the solicitor bill.
What agent could do to change your mind?
Send someone to fix the heating (in December) and a leak in less than 3 days.
Start giving back people's hard earned deposit.
When managing a property, stretch a bit by doing more than collecting the rent.