Subway Subway purposely over charged me and gave me undersized drink Lockhart Texas

i went to subway and ordered a 5 dollar footlong and made it a meal. i was over charged 50 cents for the meal wich their response was that its just the way the computer rings it up there was nothing they could do but gave me the 50 cents out of their tip jar.
the drink iwas charged for was a 32 oz fountain drink and i was given a 20 oz cup not the large 32 oz size. their response was that both sizes are the same price. but i finally was able to get the larger size.
this is something that is done to every customer that makes their sandwich a meal. wich most customers dont notice.

william
Lockhart, Texas
U.S.A.