We are having several problems because we hadare excedded the limiteding the bandwidth of theour internet service.

Bandwidth is the proper term here, another person suggested quota, which would convey what you mean. However, bandwidth is the proper technical term.

Actually we have a serviceWe have a bandwidth of 100Mbps and we would like upgraded this service upgraded.

Could you tell me how to updated this hired service?

Redundant sentence, you already asked for the service to be upgraded.

Thank you and I hope for your quick answer.

We are having several problems because we had excededed the limit of the internet service.

Actually we have a service quota of 100Mbps and we would like upgradedto have this service upgraded.

Could you tell me how to updated this hired service it (this service again would be repetitive)?

Thank you and hope for your quick (usually an answer is prompt but quick is also fine) answer.