How to ask for more hours (AUS)

Hi I’m fairly new and have been working for almost 2 months regularly getting 7 hours per weeks but now as holidays have come I’ve been dropped to one 3 hour shift per week despite being a good worker, not needing to be told what to do, showing up on time and getting along with other workers and managers.

How do I go about politely asking for more hours? I sent them an email and told them that I’m more than happy to come in 12 hours per week and that I’m available but no response. I don’t want to sound rude and I don’t think it is personal as I’m new and the stores under new management but I need at least 7 hours per week, preferably 12. I did 14 hours last week as I got called in and picked up a shift so I can handle hours.

Thanks.