Another key question

I've only got one key for the car and will probably order another from the dealer soon, although for £227 I may wait a while but the key I do have (pictured) has a split in the lock button. Can I replace the case with one like this chrome one on ebay? http://www.ebay.co.uk/itm/Mercedes-B...item19da6d569e

and is it easy to do?

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