Call centre has their own time zone

Called 10217 at 16:50. Voice telles me that I've reached them outside their operating hours. Fair enough. Then the voice proceed to tell me that their operating hours are from 08:00 till 5:45pm. It seems that they have their own time zone? Earlier I spoke to an operator, who, after I explained my problem, calls that have not been made from our number were being billed for. She then directed me to their so-called ***** line ***. That voice told me that they were an independent section and did not deal with billing enquiries. The merry-go-round continues.