Swapping a garage door panel yourself is possible on newer doors where the manufacturer still lists the part and the stiles are standard. It's a different job on a door built around 1970, where the panel has to be ordered against specs that may not match anything current, and where the door is under spring tension the whole time you're working near it. We won't talk anyone out of trying a cosmetic fix - a scratched or lightly dented panel that still seals fine doesn't need a service call.
Where we draw the line is structural damage: a panel that's bent enough to bind the rollers or crack at the hinge point. On an older door, forcing a mismatched replacement panel into place can throw the whole door out of square, and that's a harder, more expensive problem to undo than the original dent. If you're not sure which category your damage falls into, we'll look at it before you order parts you can't return.