
In all the 30 odd years I have had dogs and I have had many large and small it has never taken me longer than a week to housetrain one completely, whaterver the age or size of the dog that has come to me.
It is very easily done if you are willing to be completely dedicated for a week and in this time you can also teach them to go on command.
Firstly with an older dog that now has more control over its bladder, if any health problems have first been excluded then I would make a point of EVERYTIME the dog goes out in the garden going to, yes its cold possibly wet, but thats what coats and brollys are for and discomfort freezing in the garden for a few days is better than a ruined house. There you stay playing with your dog or whatever till it has been. While it is actually going in a really happy excited voice you say clever boy or clever girl, or something similar that you won't use at other times. On walks if your dog goes you repeat excitedly the same words and always masses of praise.
Hopefully following this to the letter your dog will not have any accidents indoors but should it then you silently with your back to your dog clean it up totally blanking them. telling off is giving them attention which they thrive on. If you catch them in the act then silently remove them outside to finish and if they do finish outside then you praise for what is done outside.
You should then find at night or before you go out you can just say to your dog "Go be clever boy/girl and they will go. Once the accidents indoors stop it is as well to watch from the door or a window for a while to make sure everything is expelled and still praise as it is happening and on walks throughout the dogs life when they go I still tell them they are clever so reinforcing happily a command.
If I have a puppy from around 8 weeks it is easier to teach as they need to go so often and easily by 12 weeks at the latest i would expect to see them going on command if they need to. May mean a cold house with doors open for about a week or you shivering outside but it is well worth it in the end.
Remember telling off or getting cross is still the dog getting attention the worst punishment is to be ignored.
Good Luck
Bev