Today as I was transferring trains in Nagoya the station attendant was shouting repeatedly「ありがとうございや」. Doing a search on the internet revealed that this seems to be a shorted form of ありがとうございやした but I have never heard of this before.
Is this from a specific dialect/age group/group Is it's usage just a simple replacement of 「ま」in 「~ました」 Can this be done to any verb, or is it limited to 「る」ending verbs that conjugate to 「い」in 丁寧語 (polite speech)?