Golf Rules unable to escape from a bunker

Question
During the course of a round of golf my playing partner hit a shot into a green side bunker in which there was an abundant amount of soft sand.
As he walked into the bunker he left shoe imprints that were almost a foot deep.
He tried to play a shot out of the bunker and failed to get out. For his next shot the ball had settled some six inches into the sand and left no shot.
My playing partner then proceeded to play about 20 shots in the bunker and eventually had to retire.
The bunker was in such a bad state that he could not have dropped under penalty within the bunker without the ball sinking well into the sand and leaving an unplayable shot.
He also did not have the option of dropping outside the bunker under penalty of one.
He also does not have the option of playing stroke and distance because he had already played a shot in the bunker.
Are there any rules that would overcome circumstances where the player feels it is impossible to get out of a bunker after trying and failing a number of times?

Note that this was a one off occasion and the bunker in question is normally playable.

Thanks

Andrew

Answer
Andrew,

Here is the rule.

If the player deems his ball to be unplayable, he must,
under penalty of one stroke:
a. Play a ball as nearly as possible at the spot from which the original ball was last played (see Rule 20-5); or
b. Drop a ball behind the point where the ball lay, keeping that point directly between the hole and the spot on which the ball is dropped, with no limit to how far behind that point the ball may be dropped; or
c. Drop a ball within two club-lengths of the spot where the ball lay, but not nearer the hole.
 If the unplayable ball is in a bunker, the player may proceed under Clause a, b or c. If he elects to proceed under Clause b or c, a ball must be dropped in the bunker.
When proceeding under this Rule, the player may lift and clean his ball or substitute a ball.

You can see that since the ball was in the bunker the ball has to be dropped in the bunker. In this situation I would have taken this situation to the Club Professional to see what is his/her decision. They may have the authority to invoke a local rule.

Thank you,

Michael