when i have had issues with telco services that we were the reseller for, and have had the opportunity[need] to speak with the sales rep, or channel manager for our reseller relationship, and have referred to the customer as 'our' customer. i have often found that the technician i speak to for some reason makes it a point to refer to the customer when speaking to me as 'our' customer, and they seem to have a more cooperative attitude.
i do also feedback to the channel manager when i get good service from a technician, or good issue resolution results. i mention the technician, sales channel rep., their good response, and the fact that i also mentioned thier excellent performance to 'our' customer. i do not make it up, but when i get what i want, need, or desire for 'our' customer and feel the telco response was above average it seems to make the telco we resell for more responsive to my requests, at least in our local sales area where i foster a good personal relationship with the channel. my sales guys have no probelm giving me the contact info. for the most powerful person from the telco who has ever tried to endear themselves to our company to apply leverage, or honey when that may help as well.
when your telephone system vendor is the telco reseller, the telco is a bit less likely to think they can baffle the customer with bullchit, and when they see you have that document on file that enables you to manage their telco services they know they can not go around you to report back. single point of contact has its advantages.