Slate copings - How to bond them on!!

[dig dug dan]

Hi people

I did a job recently using stonemarket truslate, and cut 600 x 300 lenghtways to make some copings for a wall.
Problem is, the customer has complained that they are now lifting off. I used a 3-1 soft sand cement mix, but it doesn't seem to have worked.
Is there a way I can just lift off the copings leaving the bed, and "Stick" them down with something. I am loafed to chip off the old mortar as it will spoil the rendering on the front of the wall.
If there is something, where can I buy it?

cheers

Dan

[lutonlagerlout]

hi dan ,i used some of marshalls walling adhesive recently and that stuck the dry stone look-a-like blocks like the proverbial to a blanket,im sure ronacret probably do some super doopa sticky stuff as well
try his website
cheers tony LLL