Completed Operations Coverage Under CGL Form?

Q

Our agency insures many bus companies, all of which are insured under ISO commercial general liability policies.  Many of these clients perform occasional maintenance or repair work on buses owned by other bus companies. In doing so, they create a completed operations exposure in the event that the other company's bus is involved in an accident and it is alleged that our client's repair work was the cause of or contributed to the loss. Would you confirm for us that the described completed operations exposure is covered under the ISO CGL policy and, if it is, inform us of modifications that could void or jeopardize that coverage?