I quite twice before with Chantix within a week but am having a hard time this 3rd time

I'm having a hard time quitting this time with Chantix. I quit twice before within a week but ended up starting again with friends who smoke. I was wondering if any others have had trouble quitting with Chantix. I'm at the end of about 2 months of Chantix this time and haven't found my urge to smoke going down, Should I continue taking it since I have to pay $130 a month for it or should I stop taking it and try some other way? Any advice or suggestions greatly appreciatedl!