Holland America Line review: refund of an overcharge on board the previous cruise, from guest relations department at Holland America (HA) headquarters

My mother's shipboard account was overcharged $10.08, a couple of days before the end of the cruise, for some beverages that we did not drink, a couple of cokes from the minibar and a bottled Panna water. This occurred a few days before the end of the cruise. We were on the Holland America Nieuw Amsterdam, booking number 2NCL8K, 28 day cruise, dated from Sept 29, 2024 to Oct. 27, 2024. We spoke with our cabin steward, Risman, and he told us that the account would be credited. We kept track of the account, and no credit shown.. We tried hard to get the refund while we were still on board, and spoke with the front desk more than once, one time with an attendant named "Princess" as per her name tag, and she assured us that the account would be credited within the next 24 hours, and it was not, so we returned to the front desk again the next day, and spoke with an attendant named "Mo." And he told us the same...credit should appear within another 24 hours, and again, it was not. Then it was time to disembark. After the cruise was over, I had emailed Guest Relations department at Holland America 3 times (Nov, 8th, 13th, and Dec. 3rd, 2024), with Case numbers 10458920511. 590328647384, 590033096535 that came from each of those emails (possibly not in that order). After that, I called them several times since the fall 2024, and was told every time, in varying ways, that we would receive the refund, and we STILL have not. I spoke with Mitch in Dec, 2024. I spoke with Robert on January 23, 2025. I spoke with a lady who calls herself "Jazz" on March 17, 2025. I spoke to Star on April 9th and again on the 11th, who further guaranteed me that we will receive this credit, either as a credit on Mom's credit card account or a paper check sent in the mail. I was told 7-10 business days, but that was months ago when I spoke to Jazz ! Was also told that my mom would receive an email stating that the refund is coming, and she has not received that either. I spoke to one more person after that, who would not give her name.
My Mother and I are 5 star and 4 star mariners, respectively; therefore we have been loyal cruisers to Holland America. I respectively ask that this be addressed. We have been waiting a long time, and have been chasing them for about 8 months now. I would appreciate any assistance in facilitating a resolution, and a refund. Thank you !