Its a simple system to use and very strong when used in the correct way, you must make sure to build a good apex.. I havent had any trouble with fills, perhaps your clients arent using cuticle oil regularly and the gel is getting brittle and lifting away when you are filing for an infil. Its so difficult to say when im not able to see the problem close up. Perhaps there is an educator in your area who you can take a conversion class with ?
Im happy to help. 8 watt bulbs wont be good enough to cure lechat products so dont use that lamp. However lechat products are designed to be cured by any 9 watt lamp. If you have. A 4 bulb lamp it will be cured in 2 mins. If you are doing very dark colours you may need an extra minute as the density of the pigments slows down the curing.