Welcome to the Bunnings Workshop community @KathyB. It's fantastic to have you join us and many thanks for your question.
You might not need to change the whole shower but you would need to install a new shower doorframe. It would be helpful to see some pictures of the type of shower and frame that is installed. This will assist our members in assessing whether you could remove the old frame and install a new one.
We look forward to hearing more information about your shower and providing a solution.