Well, that looks rough, but I am certain a frame straightening service could deal with it for some indeterminate amount of cash. If it were mine, I would get some really large Oxy-Acetylene bottles and a big torch tip and start working with the tubes red hot. Clamps across the flattened portions; holes with screws that can be pulled where the dents are, etc.; all while it's red hot. Having spewed this, I admit I haven't done it, it's just the approach I imagine. No doubt, it would need to be developed and modified during the learning process.
Richard L.
I tried to see if Google translator would make sense of all this, but I was never satisfied with the translation, so I hope it makes sense as it is. "Spewed" meaning, "spoken, maybe, too much."