GMAT Critical Reasoning (CR) | Re: Bert's Refuse has decided to add salvage to its

Bert's Refuse has decided to add salvage to its business services and has offered its client, McCloud Metalworking, the following deal: Bert's will deduct the amount it receives for selling McCloud's scrap metal over the next year from the cost of refuse removal for McCloud. McCloud will pay an estimated monthly bill and, at the end of the year, Bert's will adjust the bill to reflect the true profit from its salvage of McCloud'sscrap.

Which of the following, if it occurred, would constitute a disadvantage for McCloud of the plan described above?