Just an FYI. I took the $699 Avainca deal to LIM and indeed the plane was switched to Wamos. However my booking was "Avianca", not "Avianca operated by Wamos".
I didn't receive credit, but I appealed the missing credit to United and United credited me for the flight. If you ended up in this situation, be sure to appeal to missing mileage credit. (This is probably only going to work if your ticket never mentioned Wamos at purchase.)
Overall the Wamos flight was fine, about the same quality as a mainland China carrier, but more friendly. Cheers!