Excess credit

We have establish new farma manufacturing company and we have purchased some machinary and testing raw material reltaed of goods last two year then The purpose of my statement is that if two years of machinery and some raw material are being purchased in GST, then till the Finnish Goods Sale is done, the company's gst is in excess credit and whenever the goods are sold in the future, the excess credits benefit Can be taken..........And in such cases, if the seller has not return file his GSTR1 then the buyer has to pay his GST IN GSTR2A ....is that correct or not please tell me