Help needed on how I can get my money back

Hi Guys Im new to these forums iv only just registered so im not sure im posting on the correct forum ... anyway long story but I will try and shorten it ...My dilema is I lent my son and his friend the bond money on rented accomadation .. through a letting agent .
My sons friend was going to pay me back when he got his next wage any way this never happened ... I didnt worry too much as they were only going to stay in the house 6 months and I was going to get the bond back then.
my son left the property after the 6 months was up and as now moved elsewhere .... on my son leaving the house the letting agents ... who were fully aware I provided the bond have asked me to sign a document saying it was ok for them to keep the bond ... I refused to sign this and asked for it back as my son no longer lived in the property ... they have refused to release the bond as is friend is still in the house .
The letting agent is saying when my sons friend leaves the property the bond will go to him it seems I have no rights over my own money
My sons friend as no intention of paying me back ..I know iv been stupid lending this money but it was all done in good faith.
Can any one advise me where I stand ...how can I get my money back .

thanx

I notice from your location that you are in the UK. This site's focus is on Irish consumer-related issues. You might get better help on a UK site.

Sorry to hear of your problems.

ok thanx