Got nowhere with 'customer service' agents

How do I make a formal complaint?  Wasted an hour this morning trying to get an explanation of why the sums on my transaction history shown online don't add up.  Changes in the balance are more than the debits shown.  Talked to two agents.  One call dropped.  Asked other agent to escalate my complaint and got put on hold again then after about 5 minutes I gave up in utter frustration.  If Telus don't have the worst customer service on the planet it must be very close.