what year and how many miles you have?
it sounds like you need a starter. I have similar problem, I rebuild mine for less than $10.00. it turned out two of the four brushes were very short. You can DYI and get it rebuilt for about $60 at the shop.
09 GL320 Bluetec 65K+
07 E320 Bluetec 43k+
05 Nissan Frontier NISMO 4X4 72K+
07 Kawasaki Vulcan 900 5k+ gone
87 300SDL 158k+ gone
91 300D 113k+ gone
83 300SD 220K+ gone
89 300E sold
87 190E sold
83 380SEL sold