your fixer is correct about using wire but there are some considersations ,wire fixing is not allowed above first storey height internal or external so above 12-14 feet you would need a stainless steel plate fixing or a toggle and tang fixing ,the wire you need can be purchased from knight's precision wire in Potters Bar,again internally depending on the use of the area you have to be careful using resin to anchor the fixings as there are fire restrictions on the use of resin as it melts at a low temperature and plaster of paris or neat
cement is somtimes insisted upon though some 2 part chemical fixing do have the required heat resistance but i would check with the stone federation for the current
regulations as I havent mechanically fixed stone/tiles for several years ,the last job i did this way was 2007 i will see if i can find the old e-mails where i ordered my fixings from and post you the link but by far the cheapest way would be a flattened stainless threaded bar with a 2mm hole punched in it and a stainless 2mm bar/pin dropped through the hole into the stone/
tile ,this is known as toggle and tang, good luck with the job and remember to post some pictures just checked out who i used here is a link
Ancon and they made my fixings with a 5mm hole punch in them