Costco Insider Code Question

I'm trying to port 4 lines and get 4 new phones on Go5G+. The nearest Costco isn't close. So I tried the 800 number a couple times seeing if an insider code was available. The last rep told me they don't have codes at the 800 number. Is that true or should I try a few more times calling to see if one is available before giving up?

He also told me that if I had a code from a T-Mobile rep, they can apply it when doing the order. Of course, that's not something folks would give out for another person's sale. So, not sure what he meant.