Make sure you don't pay until all work completed!

Just want to make sure that people don't make the same stupid mistake as me, had an electrician to do some work which he did very well said he would come back to fix the house alarm system he seemed to be trustworthy so paid him and have not seen him since, have texted him several times, at first it was just excuses, van not working etc. etc. now he does not even reply, BE WARNED- SDC ELECTRICAL INSTALLATIONS LONGFIELD KENT DO NOT USE THEM if you do make sure all work completed before paying.
I have noticed that he is not listed on any website that has reviews not even Yell.Com in future I will use a site where reviews can be written I think it might be safer.