@Gerardo Lewis
You are a medium between the owner and all of the responsibility necessary to manage the property. You are in no way shape or form responsible for paying for work done to the property. Your job is service, service, service. Organize the contractors, get them the best rates, follow up and check to make sure they did everything that was asked. You do not want to get in the habit of paying for your customers expenses. What if the contractor discovered something much more expensive that needed to be done while completing the work? Are you then now liable for paying for something that was $1,000 instead of $50?
So in the future do one of two things have them pay for the service done to the property on a case by case basis, this will be most of your customers. The other option is to have them setup a refundable expense account for their property, sort of like a security deposit for a home but it’s sole purpose is to fund expenses for repairs. So if they really want to get the repairs fixed immediately but they’re hard to get ahold of you can still get the job done.
That second option Is in most cases unnecessary, the truth is most of your contractor work will be paid once the job is completed and only for the expensive jobs will you have to pay partially upfront so their shouldn’t be too much of an issue having your owner pay for a job even if there is a lag time on communication and they live far.