Are you on fibre or DSL? Have you contacted Telus directly? Sometimes plans are no longer offered online but may be still available if you spoke to a person in Sales. I know for me on fibre, the lowest plan available in my area is 250mbps.
Log on to your My TELUS account and then go here to see the plans available:
If you don't see the 75 plan it may mean that your area now has fibre and you can only renew on those plans.