Carid is a dropship company, like a lot of online merchants and drop ship is the rule for a lot of automotive and rv aftermarket stuff. They have low overhead because no storefront is maintained, and no warehousing. They're simply an order processor / middleman. You get the price because the merchandise is shipped directly from the vendor to you. Carid never touches it. They just take a percentage.
For what ever reason they had a miscommunication between them and the vendor. Whose fault matters not. The bottom line is neither they nor the vendor will admit and eat the mistake. They will refund your money but that's about the limit of their liability. It's just the chance you take shopping price with drop shippers. I have had the same type thing happen more than once. You can run into the same thing with some of the sellers on Amazon that are not "fulfilled by Amazon".