Yes, you can proceed to engage a law firm to issue letter of demand. The costs for issuance of letter of demand may differ from one firm to another; and is normally subject to the complexity of the matter.
Apart from engaging a law firm to issue letter of demand, you may consider to file a claim against the supplier at the Tribunal for Consumer Claims Malaysia to claim for any loss suffered (in respect of any goods or services purchased or acquired) in a less cumbersome manner and at a minimal cost. The award will be made and shall be deemed to be an order of a Magistrate’s Court and to be enforced.
On the other hand, the police do not deal dispute and/or affairs between supplier and customer unless there is an element of crime therein.