Sorry to hear about your predicament.
You are probably right that it is the lens - try carefully cleaning the AF contacts on the lens using an alcohol swab. Make certain that the camera battery is fully charged. Now try the AF mode operation.
If the problem persists, put the camera in Manual Focus Mode and look for any 'binding' as you focus the lens.
Then try Canon's technical service guys either on the phone or via chat.
If after all these efforts, the problem still persists, its time to make a decision whether to use the lens in Manual mode, or whether to send it in for repair after weighing the cost of repair Vs the cost of replacement.