Resellers have to buy credits up front. When they sell onwards they have already paid for the service they're selling

What I do, at the start setup and outline costs and rules in regards to basics like maintenance and payments etc, then I send them an agreed monthly invoice and then give them 7 days grace if they say before its due they're struggling but if I feel it's not genuine (done this for over 10 years so get a gut feeling)... They get cut off like they would with any company for not paying their Bill and their clients would get paused until they do so then after a further 7 days accounts are deleted except a random few that he has paid for with monies paid prior to not paying (I work this out on amount paid and then compare it to reseller rates and keep subsequent total of users to equal amounts paid) then he and his clients got exactly the amount he paid for so their can be no discrepancies.