If the bow they took the cams and strings off of was not the same model as the X-Tec you bought, then there is a very good possibility they screwed up. For example a Razortec at 29" will have different length string and cables even though the cam sizes are the same as an X-Tec at 29"
If the two bows were not identical (i.e. Both X-Tecs) then you need to take the bow back to the shop and have them A) Order you the correct bow, or B) Order the correct cams and strings for your existing bow. In either case 64# from a 70# bow is not correct.