E-Cigarette only works for the first few weeks

I purchased a Playboy E-Cigarette from The Grove Superspar in Nelspruit Mpumalanga. The 1st one I purchased worked fine for the first 3 months and then the vapouring stopped. I purchased a 2nd one - when it started to get dirty, I cleaned it and after that it was not working properly anymore. Thinking maybe I did something wrong - I purchased my 3rd playboy e-cigarette. Regretfully I realise that I have wasted about R1200.00 on these 3 items and all seemed to have the same problem. After getting dirty after a few weeks of using, I cleaned the 3rd, again after carefully researching the proper cleaning methods, thinking maybe I did something wrong, but it seemed that I did it the rite way the first time as well. I cleaned it very carefully. Now you have to really puff a few times before getting a fair amount of vapor. Not a nice smoking experience. There are much cheeper e-cigarettes on the market, but I decided on the playboy to get a good quality product. This was definately not a better choice. This is very frustrating. I need to get this sorted as soon as possible. I have purchased a cheeper e-cigarette in the meantime, but would like to use my playboy cigarette again