Complex sentence: On the advice of their friendly maid they go to a service to find them a home, (which turns out to be an unkempt council flat) and find it deeply unpleasant until they "do it up".
Split into simpler sentences: On the advice of their friendly maid they go to a service to find them a home. The home found for them turns out to be an unkempt council flat, and they find it deeply unpleasant until they "do it up".