and it did not buy. DO they have the right not to let the transation go through? Any suggestions please?

Stock trades are not always instantaneous. There are a number a factors that determine if a trade goes through at any given time. l use an online service. Sometimes the transaction takes seconds;,others hours or even a day. Today was a weird day with trading. If you set it to ''Good to Cancel'' you should be fine.

l have had days like that too!!
It seems that ordinary investors like u & me can only grab onto ''buys'' or ''sells'' when the market is acting fairly normal & there is time for our trades to go through the system. But when things r moving as fast as they r now, & the prices fly right past our target prices in such a hurry, our trades just do not get the opportunity to go through. That is all. My suggestion is this: Watch out when a real stock market crash comes through! No matter what price u place into ur system, it wo not catch & the market will keep crashing lower & lower & ur targets wo not take hold. At that time the only thing to do is to place a sell ''AT MARKET'' & specify a limit price of perhaps 10% less than what ur computer shows to u as the current price that exists. What will happen is that ur stock will sell but at a slightly lower price than the current market price, sometimes at the very bottom of the price range that u have just specified.

Under no circumstances should u EVER place a sell or buy order without placing a limit on the price, because if u do, u will find that u will buy the shares at $25 per share instead of the $2.10 per share that u wanted. l have seen it happen to other people & they have been completely wiped out by it, so be very careful.

Everyone wants to apply a conspiracy theory or Big guy vs Small guy.

When your limit order gets hit, it becomes a market order. But there may already be other market orders waiting, or before your market or becomes available, like in fast markets, the waiting market orders trade first, or maybe there was only one trade at the lower price, then it was bid back up.

There are many ways a limit order can get bypassed.