the only frustration i have is in match when the score is something like 2-1 to me i make a sub and just as the sub comes on they score this happens to me all the time its getting to the point where i don't make subs unless am losing or beating the opponent like 3-0
if you want a quick fix do a player search and find the best CM that there is an buy him, or the only other way is to do what Scotty98TR said and develop a youth player it may take time but by the sounds of it you look like your in it for the long haul so it souldnt really matter how much time...
There's only 2 centre backs you should be thinking to buy for Real Madrid an they are DEDE and Kurt Zouma. On my game Zouma turned out to be the best CB on the game he is an absolute beast but it might cost you about 25 - 30mill.
why not try Sandro from Tottenham he turned out a beast on my save, depending on were you finished in the league try and sign Vidal from Juventus he can do everything in midfield attack and defend might cost you a bit but you wont regret it ;)