My DME used to be Lincare was equally terrible. They were awful. They never had replacement consumables in stock, and I had to deal with months worth of delays to get things I needed. That’s why I went to CPAP.com (like OP) for a time. It was annoying having to coordinate with my insurance company to get reimbursements since they didn’t direct bill, but at least I would always have my equipment on time. (As a bonus, it was cheaper than Lincare to boot.)