They are giving you excuses for the mistake that they've made. They shouldn't have spent the unconfirmed transaction with extremely low fee that clearly wasn't going to confirm any time soon. The network congestion didn't happen all of a sudden during that transaction, the fees were already high when that tx (6f06c23dd9...) was created and it was clear that 3 sat/vbyte is very low.

Besides it would have been understandable if the unconfirmed tx was only the previous one, but they are creating a long chain of unconfirmed transactions and if one of the ancestors (like 6f06c23dd9...) uses RBF to bump the fee, the entire chain becomes invalid and they'll have to resend all of those transactions again manually.