No legal advise can be given without a full review of your situation. As will become evident from this answer, there are many aspects to your situation that can impact the final result. An immediate in-person consultation with an attorney is, therefore, suggested.
That being said, there are a couple of practical matters to consider. If you receive a call from the Sheriff stating an intention to evict and you do nothing, what is the likely result? The Sheriff will, presumably, follow through with the action and an eviction will follow. As such, that may provide the simplest and most practical answer to your question.
Additionally, being concerned over "conceding" matters is not a constructive way of viewing the situation. A phone call in response to a notification can simply be a response and inquiry seeking clarification. It would allow you to inquire if there were other available options, such as a short term rental option or a negotiated stay of eviction (with monies paid to the lender) or some other option other than the apparent pending eviction by the Sheriff. The point here is that, under Illinois law, only the Sheriff has authority to remove people from residences. Therefore, if there was such a call made, the standard foreclosure procedures would require both a prior judicial sale with a purchaser and that sale being approved by the court. If this process has been followed, there would be nothing to "concede" as the court has already decided the matter and entered an order allowing for the eviction.
Since no legal advise can be given either in this response or by an attorney without a detailed background, a trip to the courthouse to the clerk's office may be in order. You can review the court file, copy the docket sheet, and look to verify that all of the required actions occurred leading up to eviction. You could also look to have the matter brought back to the Judge via motion and ask for additional time to vacate the property.
With an impending eviction by the Sheriff, you should speak with an attorney regarding your situation. It may be that some defenses exist or some form of extension can either be negotiated or sought from the Judge. During any such interview with an attorney, one question that will likely be asked is what did the attorneys for the lender say when you asked for additional time to vacate? And the next likely question is what court orders were entered and when?