Two things mentioned.  1.flat feet. 2. Heel raise required. To correct flat feet an orthotic is required such as http://www.yourfootcare.com/html/insoles_orthotics_2.html  To simply raise the heel this could be done with a silicone heel cup which will raise your heel by approx 1cm,http://www.yourfootcare.com/html/silicone_heel_cups.html.   You would need to be certain this is the maximum you require. When larger raises are incorporated in to shoes they are usually specially made. An Orthotic will correct the flat feet but the heel is not so much raised but corrected in its angle. Let me know what you think.