Can I get the sale cancelled, if buyer only makes a part payment?

[5000gem]

I have posted about his a few days ago.

After exchanging an extraordinary amount of message with a buyer (25+), I finally have a "uncollected funds" amount when accessing my bank account (assuming it is from this buyer, which I can't see yet). 

I have already been through a cancellation request which was declined by the buyer.  The amount paid now is short of what is owed.  Can I return the amount to the buyer, as frankly I am over it or do I have to ask for them to pay the balance and how long do they have to pay the rest.

[putney32]

THEY have absolutely no protection whatsoever if they paid into your bank account so whether you refund (if you can find out their bank details) or not is up to you.

never, ever ask for a mutual cancellation if they are a non payer, go down the dispute road every time, and that'll block them from leaving any feedback.

as you have their money (or will have by Monday), you have to decide how you are going to proceed, but be aware they can leave you a neg. fback (and sounds like they may do anyhow).