What service is this?

My Navara for service, lady was friendly and all that. told her i need 90k services and pls check my speedometer and hooter something isnt right. So they did the service and when i got back to fetch the car i was told they didnt do the hooter and speedor cause the parts department is closed for stock taking. They will call monday with the price and labour to fit the diagnostic issues of the vehicles. But monday came no phone call or email untill today. So i called around cause i was given the parts needed to be bought. But sadly all the nissan ive called said the part i was told to buy doesnt make sense for the problem. I was told to buy an airbag model. And i have wasted money calling one dealer to the other and none of them want to supply the part cause it has nothing to do with my problem unless i insist. Even the dealership that serviced my car its own parts department doesnt think this sounds right. Infact he said it straight \IT CANT BE\". Im now even starting to doubt that the parts department was closed. Cause i think this wasnt checked as per my request on the day of service so i can book the car in to pay more or something this sevice i got feels very dodge. "