Outranked by 3 pages from Best Buy

Hello guys,
It seems recently Best Buy found one of my keywords and started to ranking for it.
The problem it's not that though… the problem it's that I lost 3 positions. Google shows 3 pages from them now on the first 3 positions. As you can guess, losing 3 positions at once it's different than losing just one positions. Why this is happening? Is it just a dance or will google remove two of that 3 pages in the next weeks in your opinion? Should I start again building links now? Do I have…

Outranked by 3 pages from Best Buy