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Depending on the hosting situation, it might be possible that the issue could be fully resolved without involving the other party but I would not recommend jumping into this on your own. Not that the basics are terribly difficult but there are a number of basics you would need to wrap your arms around and there are numerous non-basic things to check and verify before you pull the trigger on a fix. Doing it incorrectly could easily leave you with a bigger pickle than you have now.  I recommend that you get very familiar with the topic via guides here on Moz and elsewhere before doing it yourself or have someone with experience take care of it for you. But to partially answer your question, yes, you can install redirects after a year or even longer.  Whether they fix the issue you are describing would be quite another thing, however.