You won't be offered the steroids indefinitely, as they increase the risk of osteoporosis.
But since they aren't working, here's an alternative approach.
It's known that periods of inactivity can lead to a flare up of the symptoms of polymyalgia, which suggests that there might be a benefit to be had from improving the circulation. Would you consider trying some whole-leaf Ginkgo Biloba for 6-8 weeks?
The "whole-leaf" is potentially important here, as most ginkgo products focus on the blood thinning component, whereas in its natural state, this element is secondary to its relaxing effects on blood vessels and oxygen delivery to the tissues. You can also take whole-leaf ginkgo with any blood thinners from the doctor, unlike regular ginkgo products.
The other thing to try is some magnesium in the form of magnesium citrate at 200mg morning and evening. This helps relax muscles but could also improve sleep, which I'm sure must be poor, in turn helping you cope with the pain better.
If you are a really bad sleeper, try some Dormeasan drops as the Valerian can also help muscle pain.
Polymyalgia is an inflammatory condition and while we don't have products as powerful as those prescribed to you, an alternative approach combined with pain management through improved sleep and the dietary adjustments featured in my blogs - Dealing with pain - should help you a great deal.