Sorry to hear this happened to you. Likely no recourse other than the points already being refunded via AF. Perhaps some sympathy miles from DL or AF for the troubles, but they are not going to reimburse the UA ticket. This is a situation where I think you just got unlucky with agents at both DL/AF. I've found many DL agents are clueless that an eticket must match the PNR (except in a few cases where it's revalidated - and a name change is not one of those). The DL agent shouldn't have made the changes to your reservation and should have insisted they be made with AF, who issued the ticket. The first AF agent shouldn't have sent you to DL either just because everything was operated by them as AF was the owner of the ticket. Classic case of airlines pointing fingers at each other.

In the future, carefully check that your ticket and PNR match exactly. When dealing with DL, ask the agent for the JV desk or global ticketing support. They can usually fix things frontline agents can't.