Problem connecting with call back

I've had an ongoing issue with Telus callbacks. I'll arrange a callback re: a technical or billing problem. The chat service on a Telus website will promise a callback at a specific time, often the following day. Prior to the appointed time, a Telus Update will arrive by SMS saying an agent will call soon and asking me to make sure their Callback numbers aren't blocked on my phone. It also advises to answer with Hello and that there will be three attempts to connect. So far so good. But when my iPhone rings (from 1-866-558-2273), I hit a snag: the Interactive Voice Response requests me to press 1 to connect with an agent. But when I do so, the tone isn't acknowledged by the system. Pressing 1 over and over does nothing; the massage simply repeats that I have not responded and says there will be another callback. So frustrating! When I finally got through to an agent by using my landline this morning, she solved my original issue and said she would forward notes on the IVR glitch to the right technical department. In the past, however, I haven't heard back about the issue and doubt I will this time. Any suggestions?