Further to previous discussions regarding audio suppression, I did contact Encore Ave, Movie Central and Turner Classic Movies as you suggested. I received just one response - from Movie Central which is below.
"While Movie Central
may occasionally experience intermittent technical problems, we are not
currently experiencing any technical difficulties with our audio or video
signals that we are aware of. You may want to contact your television service
provider to inquire about any technical difficulties they may be experiencing."
Although they don't admit to using audio supression, the inference is that any audio difficulties rest with "the television service provider" - i.e. Shaw.
Can you shed any further light on this? Has no one else complained?