Ask the store manager why you are not getting 40 hours. Generally, you as a full time should be getting 40 hours before the part time people get their hours. Most contracts guarantee full time 40 hours a week. Under special circumstances, they can give full time less hours but they would have to give every full time less hours. It is possible you might have lost full time if you called in too many times. Under our contract, one needs to average 36 hours a week to keep full time status.
If these 27 hours weeks have gone on for a long period, it is possible that you lost full time status. Check your pay stub to see how many hours you are getting for holidays.
The store manager and department head are the only ones that can explain why you are not getting 40 hours.
I was concerned in my store about being classified as full time which I don't want. My manager said FT status is 40 hours a week for 8 straight weeks. Working 40 hours for 7 weeks then getting say 39 hours would still be considered PT he said