You realize the neighbourhood is filled with customers, just like you, who offer knowledge and support to help others with their use of Telus services? As such we have no ability to effect change to a bill.
Usually, Telus calls and emails clients once a bill is past due, and in most instances does cancel services after some time of non-payment. My suggestion is to contact Telus, with supporting information about your son's disability, and politely ask for a re-consideration of the bill. However, at this point, the fees may have been sold to a collection agency so your avenue of appeal may be there instead of Telus.
Generally telecom companies have dollar amount limits and time frames they follow before they disconnect. So depending on how much was owing and if any payments at all were paid it could effect the disconnection date
Ultimately if somebody doesn't need their service or want it anymore as customers we should make some decisions on our own. If you continue to use a service, by all means you should pay for it. The company does send out statements each month with amounts owing and for what time, with details like overdue balance etc as well. This can't be all on the company themselves.